Fontan operation is the connection of the systemic venous return to the pulmonary arteries, performed in patients with single ventricle physiology. The Fontan circuit is commonly fenestrated because of early postoperative risks such as high systemic venous pressure and low cardiac output. As it causes progressive cyanosis and increased risk of paradoxical embolism in the follow-up period, occlusion of these fenestrations is generally suggested. Successful closure of extracardiac Fontan fenestration with atrial septal occluder in a 10-year-old girl is reported herein. To our knowledge, this is the first such report from Turkey.